UCR, or Uniform Crime Reports, are the name of the data sheets produced by the Federal Bureau of Investigation for figures about crime. The three highlighted reports on the FBI website are the UCR for "Crime in the United States", "Hate Crime Statistics", and "Law Enforcement Officers Killed and Assaulted".
UCR are used to disseminate information that can be useful to a number of parties, including law enforcement officers, news media, advocacy groups, chambers of commerce, community organizations, and schools. Groups and individuals can use UCR to evaluate the level of violence in specific area over a certain number of years. Legislators can also use the findings from UCR research to argue positions in bill drafts or legislatory hearings.
However, the FBI itself warns that the UCR should be analyzed only in conjunction with other data sets because the UCR cannot give an exhaustive representation of crime statistics. Crime rankings, therefore, should not be solely dependent upon the UCR results.